There are numerous environments in which peristaltic pumps are used to deliver fluids. Peristaltic pumps are often advantageous because of their ability to deliver relatively accurate doses and to deliver metered doses over a prolonged period of time. Peristaltic pumps may be used to dispense liquids in laboratories, to regulate fluid flow in automobiles, and are frequently used in the medical field to deliver fluids to a patient. These fluids may be those which are delivered to the digestive tract, commonly referred to as “enteral” applications, or to into the venous system, commonly referred to as “parenteral” applications.
There are many different types of enteral feeding devices, including nasogastric, esophagastric, and abdominal feeding apparatus for supplying nutritional products to patients. These nutritional products, which are almost always flowable, are available for a variety of supplanting and supplemental feeding requirements.
Likewise, there are many different types of parenteral infusion devices which deliver IV solutions, medication and some forms of nutrition to patients. Each system has relative advantages and disadvantages depending on the context.
Conventional infusion and feeding apparatuses, whether for enteral or parenteral applications, typically include a pump and various components and/or accessories for transferring the nutritional product or IV solution from a container (e.g., a bottle or bag) into the digestive tract or venous system, respectively, of a patient. These components, which may be reusable or disposable, typically include various tubing and connectors. All of the components (e.g., tubing and connectors) necessary for transferring the nutritional product or IV solution to a patient using a specific pump, are often collectively referred to as a “feeding set” or an “infusion set.” For ease of references, infusion sets and feeding sets will be referred to herein as a “feeding set” or “feeding sets” and it shall be understood that such covers enteral and/or parenteral applications.
In many embodiments, the feeding set has an inflow tubing line which connects to the container and an outflow tubing line which attaches to the patient. Between the inflow tubing line and the outflow tubing line is a piece of tubing which is more resilient and made according to more specific tolerances. This pump tubing segment engages the pump to deliver precise quantities of a desired fluid to the patient. The pump tubing segment is generally made of silicone and is more expensive, while the inflow tubing line and the outflow line can be made from less expensive tubing material which need not meet the more specific tolerances and performance characteristics of the pump tubing segment. Connectors are typically used to attach the pump tubing segment to the inflow tubing line and the outflow tubing line. The connectors may be disposed at opposing ends of a pump tubing segment for use in a linear or curvilinear peristaltic pump, or may be formed as one piece with the pump tubing segment being formed into a loop for engaging a rotor of a peristaltic pump. For ease of reference, both configurations may be referred to as a “cassette.” Thus, as used herein, the cassette is the portion of the feeding set that engages the pump to control fluid flow.
One concern with feeding sets is controlling free flow situations. When a fluid is being infused into a patient, it is usually desirable for the rate of flow to be regulated. It is disadvantageous in many circumstances to have a condition, commonly referred to as free-flow, in which flow into the patient is controlled solely by the force of gravity. Such conditions can result in a large volume of solution being infused into a patient over a very short period of time. Due to medical conditions or medication contained in the infused solution, a free-flow condition can pose health concerns to a patient. In some situations it can even result in death of the patient.
Because of these concerns, numerous devices have been developed to regulate free-flow in medical pumps. One challenge with the use of anti-free-flow devices is retrofitting presently existing pumps. While newer pump models are typically designed to accommodate anti-free-flow devices, pumps that are already in existence may lack such structures. One concern with occluders used with some existing pumps is that a free-flow condition can occur if the infusion set is not properly mounted in the pump. For example, if the occluder is mounted in a mounting structure and moved into an open position to allow flow but the infusion set is not properly wrapped around the rotor of the pump, there is nothing to control the rate of flow through the infusion set.
One solution to prevent free flow in feeding sets is the use of an in-line occluder. In such devices, an occluder or stop is disposed inside the tubing of the infusion set, typically in the pump tubing segment. The stop prevents flow through the tubing unless a flow channel is formed between the tubing and the stop. In-line occluders are advantageous because they are relatively inexpensive and lower the risk of accidentally creating a free-flow condition.
One problem with in-line occluders is that many older enteral feeding pumps develop relatively low pumping pressures. Because of this, the pumping pressure is occasionally inadequate to overcome the occluder or requires sufficient force that the pump inaccurately determines that there is an undesired occlusion downstream from the pumping mechanism. This causes the generation of an alarm which requires the response of medical personnel to determine that the tubing is in fact not occluded. These nuisance alarms waste the time and effort of medical personnel and unnecessarily disrupt the infusion process.
For example, as shown in FIG. 1, a known occluder 1 is disposed in the tubing 2 of an infusion line and mounted in an existing pump 3 as generally done with pumps such as the pump 3. The tubing is held in tension at one end by a drip chamber 4 and by a connector 5 associated with the occluder 1 at the other end. Between the drip chamber 4 and the connector 5, the tubing is wrapped about a pump rotor 6 which engages the tubing to drive a solution through the tubing.
The occluder 1 is advantageous over many other occluders because it will prevent flow through the infusion tubing if the tubing is inadvertently removed from the pump rotor. Other occluders, such as some pinch clip or sliding occluders, are opened when the tubing 2 is mounted on the pump and will not close if the tubing becomes loose.
One issue with the occluder 1 configuration is nuisance occlusion alarms on older pump models. Many older pumps, such as the pump 3, have relatively low pumping power and will detect on undesired occlusion downstream based simply on the pressure needed to bypass the in-line occluder. Thus, it is desirable to have an occluder mechanism which will allow flow without nuisance alarms when the infusion set is properly mounted on the pump, and which will prevent a free-flow condition through the line if the tubing comes off the pump rotor or is otherwise not properly engaging the rotor.
While consideration has been given to simply opening the occluder when the infusion set is mounted on the pump, this still leaves open the risk of a free-flow situation. If the infusion line were inadvertently removed from around the rotor, the rotor would no longer act on the infusion line to control fluid flow. Thus, a free-flow situation could develop, potentially injuring the patient. Thus, there is a need for an apparatus and method for providing protection against a free-flow condition while avoiding nuisance alarms.
While in-line occluders and the like have made marked improvements in the control of free-flow situations, the prevalent use of peristaltic pumps in the medical industry has led to new inquiries seeking improved manufacturing techniques, lower costs, and easier use for care providers and consumers alike. Many attempts have been made to improve the state of the art of such technology, but room for improvement remains in the current technology. There are several areas for improvement associated with the use of peristaltic pumps and feeding sets.
One issue of concern is how to improve control of fluid flow when the feeding set is not mounted in and controlled by the pump. On one hand, it is disadvantageous to allow free-flow conditions. Likewise, it is disadvantageous to allow the solution to leak out of the feeding set. On the other hand, those loading the cassettes need to be able to allow flow through the feeding set to allow for priming of the cassette prior to use. While valves have been used to control fluid flow, they often make priming more difficult. In fact, some prior technology requires multiple hands to actuate a valve to prime the feeding set.
While the need remains to prevent free-flow and leakage in the feeding sets when not being used to deliver solutions under control of the pumping mechanism, there is also a need to establish, maintain, and increase ease-of-use and convenience for users and providers. Further, it is also desirable to meet these needs while reducing material and fabrication costs.
The technology improvements offered by the various aspects of the invention described herein enable new ways to meet improve usability and lower costs due to improved designs.